An extinct group or superclass of early arthropods from the Paleozoic era, characterized by tooth-like or comb-like appendages.
From 'hadent-' (relating to the Haden/Paleozoic) plus '-tomoidea' (resembling teeth, from Greek 'tomos'). This is a paleontological classification term for ancient marine creatures.
Hadentomoidea are so ancient and weird that we're still debating whether they're a real group or a 'wastebasket taxon' where paleontologists throw creatures they don't understand yet.
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